Electric watch

ABSTRACT

A contact controlled electric watch in which the contact system comprises a first element mounted on the balance which during oscillation engages a second element and urges it in contact with a third element, the circuit for drive current flow being closed only during interengagement of all three elements while engagement of any two of said elements does not permit current flow.

[ Dec. 3, 1974 2,954,663 l0/l960 Biemiller et 3,699,762 [0/1972 1 ELECTRIC WATCH [75] Inventor: Heinz MeitingenMutlangen,

Germany Biforwuhren J. Bidlingmaier Primary Examiner-Edith Simmons Jackmon Attorney, Agent, or Firm-Parmelee, Miller, Welsh & Kratz [73] Assignee:

GmbH, Schwabisch Gmund, Germany Jan. 15, 1974 [22] Filed:

21 Appl. No.: 433,526

ABSTRACT [30] Foreign Application Priority Data Jan. 20, 1973 2302384 A contact controlled electric watch in which the contact system comprises a first element mounted on the balance which during oscillation engages a second element and urges it in contact with a third element, the circuit for drive current flow being closed only during interengagement of all three elements while en- 44 4 3m 3 H3 .c 7 4 2 B 1 8 W D MB 8 W W W5 Wmh "C u.r. "3 e us :1 C d sud U.mF ll] 2 8 555 [ll gagement of any two of said elements does not permit current flow.

References Cited UNITED STATES PATENTS 4 Claims, 4 Drawing Figures Ensign et ELECTRIC WATCH BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact controlled electric watch and in particular to a wrist watch.

2. Prior Art Watches of the type in which the time-keeping balance carries at least one coil interacting with a stationary magnet circuit so to generate a driving torque upon the electric circuit including the coil and a source of DC power being closed are known. For this purpose, the balance is provided with a terminal member which closes the circuit during a predetermined angle adjacent the zero-crossing of the balance oscillation. Since for a given voltage, given magnetic field strength and given number of coil turns the generated torque will primarily depend upon the duration of contact engagement, the contact system must be considered a very critical element of such a watch.

In particular, the contact angle not only must be accurately adjusted, but must, in addition, remain constant even after an extended period of operation of the watch.

The other contact element cooperating with the terminal member on the balance must, for the reasons outlined above, comply with quite a number of requisites. The required actuation force must be small in order to minimize as much as possible any disturbance of the balance oscillation. In addition, the contact element should be as stable as possible because shocks and oscillations to which small watches will unavoidably be subjected tend to cause deflections and/or oscillations of said element, thus there will'be a danger that the terminal member on the balance meets a contact element which has been deflected aready or has even assumed a position in which it spits the baltime resulting in very significant distortion of the balance oscillation and the desired constant angle of engagement is not maintained.

A very thin and lightweight contact element, on the other hand, will wear through very quickly and sometimes it is necessary to provide means to extinguish contact sparks which, of course, increases the cost of manufacture.

Summary of the Invention It is the object of the present invention to provide a small (portable) electric watch having a coil-carrying oscillating balance, a stationary magnet circuit whose field intersects said coils during oscillatory movement of said balance, and in which a contact system is provided to feed said coils with current from a source of DC power during a predetermined angular path of the balance in a manner that the requisites explained above will be met.

The invention provides a solution to this problem in that said contact system consists of a stationary and rigid stop member and a contact spring electrically insulated with respect to said stop member. The terminal member carried by the balance will, upon engagement of said spring, urge the latter in engagement with said stop member so to close the circuit to the DC power source. Accordingly, the system comprises two points of contact. The first contact point is between the terminal member on the balance and the contact spring, and

detrimental, it will be shown, however, that such an ar- 'rangement provides quite a number of advantages.

upon the watch. As long as there is not simultaneous engagement between the spring and the terminal member on the balance, no current will flow even during the engagement of the spring and stop member.

Another important advantage is that it is possible to provide a rather rigid contact spring so that its wear will be slight, the direction of current flow preferably being selected in such a manner that material travel due to electrogalvanic processes will occur from the spring to the terminal member. The stationary portion of the contact system will be designed as a pre-adjusted subassembly to be replaced after excessive wear has occured, said subassembly as a whole being isolated from the watch movement frame.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will be explained hereunder with reference to the accompanying drawings, in which:

FIG. 1 shows a top view of balance and contact system of an electric watch while, certain parts of the watch not concerned with the invention being omitted for sake of clarity;

FIG. 2 is a side elevation as seen from the left partly in section, of the watch portion shown in FIG. 1; and

FIGS. 3 and 4 shown in a diagrammatic manner the position of the terminal member and the contact spring during different periods of an oscillation cycle of the watch balance.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 and 2 show the balance comprising body 1, I

coil carrier 2, coils 3 and shaft 4. The balance shaft 4 is rotatably journalled in the movement frame in conventional manner and consequently is not shown. The contact system comprises a pin 5 mounted on the balance, a contact spring 6 and the stop member 7 forming part of the circuit and being insulatedly fixed (not shown) on the watch movement. Current will flow from the (negative) pole of the battery 8 via a hairspring (not shown since this manner of contacting coils carried by a balance is conventional) to balance shaft 4 and to one terminal of one of the coils 3, this terminal being connected to shaft 4. The other coil wire terminal is connected to body 1 which, in turn, has contact with one wire terminal of the other coil 3 whose otherterminal is connected to pin 5.

Pin 5 is positioned such that contact spring 6 projects into its path of movement so that during oscillation of the balance, contact spring 6 will be deflected and urged into engagement with a nose 9 of stop member 7. In this position, as shown in FIG. 1, the electric circuit is closed from stop member 7 to the (positive) pole of battery 8. A current will flow and, proper polarity of coil windings and magnetic field being provided, generate a driving torque necessary to sustain the oscillations of the balance.

In order to prevent current flow during the return stroke of the balance oscillation (shown in FIG. 3) contact spring 6 is fixed on stop member 7 by means of electrically insulating resin 11, such return stroke current creating a decelerating torque counteracting the driving force generated during the first half period.

FIG. 4 shows the normal rest position of the contact system.

The instant of switch-on may easily be adjusted by deformation of nose 9 of stop member 7. Termination of current flow is determined by the spacing of spring 6 with respect to shaft 4, said spacing in turn determining the angle of intersection with the path of pin 5. Since the aforementioned dimensions may readily be adjusted within close tolerances during manufacture,

the angle of contact engagement and thus the energy to.

be consumed may be accurately determined.

The force necessary to deflect spring 6 is smaller than that required in known watches of similar design because the spring once again deflected during the return stroke of the balance by pin 5 (FIG. 3) may swing back and engage again stop member 7 without closing the circuit nor disturbing the balance movement.

In known watches in which current flow is controlled but by a single contact point between elements comparable with spring 6 and nose 9, the spacing between said two elements must be large as compared with the spring deflection during the return stroke in order to avoid undesired current pulses. This large spacing, in turn, necessitates a considerable force to make contact when desired which results in disturbances of uniform balance oscillation. In order to reduce this effect, some known watches are provided with extremely thin springs so that already after a short period of operation, the contact system will fail due to excessive wear. To limit this wear, it may even be necessary to provide special components to eleminate contact sparkling, but these will, of course, increase the cost of manufacture.

The polarity of current flow as indicated in FIG. 1 is chosen such that material travel due to the current will occur always from the stationary component to the contact component mounted on the balance, i.e., pin 5. Thus, wear is limited to stop member 7 and spring 6. The subassembly formed of these components may be readily replaced, if necessary, while the expensive balance with the coils and other components will remain operative.

In accordance with the invention, the small spacing between nose 9 and spring 6 prevents natural decay of spring oscillations after shock or after contact actuation because of the efficient attenuation due to abutment of spring 6 at nose 9. This is necessary because otherwise, if the spring still oscillates during the next period of balance oscillation, there is the danger that pin 5 strikes upon the distal end of spring 6 thereby interfering with proper oscillation of the balance and thus with the synchronization thereof.

What I, claim is: g

1. An electric watch comprising an oscillating balance, coils mounted on said balance, stationary magnets to generate a magnetic field intersecting said coils during oscillation of said balance, a source of DC volt age, and contact means to feed said coils with current from said source in dependence of the angular position of said balance, said contact means comprising a terminal member mounted on said balance and connected to said coils, the improvement comprising that said contact means comprises a rigid stationary stop member and a contact spring electrically insulated with respect to said stop member, said spring being urged in engagement with said stop member by said terminal member, said stop member being electrically connected to said source of DC voltage.

2. A watch as claimed in claim 1 in which said contact spring is mounted on said stop member.

3. A watch as claimed in claim 2 in which said stop member and said spring form a subassembly insulatedly mounted on a watch movement frame.

4. A watch as claimed in claim 1 in which said source of DC voltage is connected in such a manner that material travel due to electrogalvanic processes occurs from said spring to said terminal member. 

1. An electric watch comprising an oscillating balance, coils mounted on said balance, stationary magnets to generate a magnetic field intersecting said coils during oscillation of said balance, a source of DC voltage, and contact means to feed said coils with current from said source in dependence of the angular position of said balance, said contact means comprising a terminal member mounted on said balance and connected to said coils, the improvement comprising that said contact means comprises a rigid stationary stop member and a contact spring electrically insulated with respect to said stop member, said spring being urged in engagement with said stop member by said terminal member, said stop member being electrically connected to said source of DC voltage.
 2. A watch as claimed in claim 1 in which said contact spring is mounted on said stop member.
 3. A watch as claimed in claim 2 in which said stop member and said spring form a subassembly insulatedly mounted on a watch movement frame.
 4. A watch as claimed in claim 1 in which said source of DC voltage is connected in such a manner that material travel due to electrogalvanic processes occurs from said spring to said terminal member. 